Do not enable any services or features that your particular file server and file clients do not require. These might include SMB signing, client-side caching, file system minifilters, search service, scheduled tasks, NTFS encryption, NTFS compression, IPSEC, firewall filters, Teredo, and antivirus features. Ensure that any BIOS and operating system power management mode is set as needed, which might include High Performance mode. Ensure that the latest and best storage and networking device drivers are installed.
You can configure the system file cache to limit its virtual address space usage and reduce physical memory usage. By default, file cache memory management might not be optimal for all workloads and applications. If system responsiveness becomes poor during file activity and the System Process Working Set performance counter has a value approaching the size of physical RAM, you might be able to improve responsiveness by limiting the file cache working set size. For a tool that can set this configuration parameter, see “Resources.”
General Tuning Parameters for File Servers
The following registry tuning parameters can affect the performance of file servers:
NtfsDisable8dot3NameCreation
HKLM\System\CurrentControlSet\Control\FileSystem\REG_DWORD)
The default is 0. This parameter determines whether NTFS generates a short name in the 8.3 (MS‑DOS®) naming convention for long file names and for file names that contain characters from the extended character set. If the value of this entry is 0, files can have two names: the name that the user specifies and the short name that NTFS generates. If the user-specified name follows the 8.3 naming convention, NTFS does not generate a short name.
Changing this value does not change the contents of a file, but it avoids the short-name attribute creation for the file, which also changes how NTFS displays and manages the file. For most file servers, the recommended setting is 1.
HKLM\System\CurrentControlSet\Services\LanmanServer
\Parameters\(REG_DWORD)
The default is 0. This parameter disables the processing of write flush commands from clients. If the value of this entry is 1, the server performance and client latency for power-protected servers can improve. Workloads that resemble the NetBench file server benchmark benefit from this behavior.
HKLM\System\CurrentControlSet\Services\LanmanServer
\Parameters\(REG_DWORD)
The default is 512. This parameter limits the number of concurrent “asynchronous” SMB commands that are allowed on a single connection. Some file clients such as IIS servers require a large amount of concurrency, with file change notification requests in particular. The value of this entry can be increased to support these clients.
Smb2CreditsMin and Smb2CreditsMax
HKLM\System\CurrentControlSet\Services\LanmanServer
\Parameters\(REG_DWORD)
The defaults are 64 and 1024, respectively. These parameters allow the server to throttle client operation concurrency dynamically within the specified boundaries. Some clients might achieve increased throughput with higher concurrency limits. One example is file copy over high-bandwidth, high-latency links.
AdditionalCriticalWorkerThreads
HKLM\System\CurrentControlSet\Control\Session Manager\Executive\(REG_DWORD)
The default is 0, which means that no additional critical kernel worker threads are added to the default number. This value affects the number of threads that the file system cache uses for read-ahead and write-behind requests. Raising this value can allow for more queued I/O in the storage subsystem and can improve I/O performance, particularly on systems with many processors and powerful storage hardware.
HKLM\System\CurrentControlSet\Control\FileSystem\(REG_DWORD)
The default is 1024. Reduce this value to reduce the size of the NTFS tunnel cache. This can significantly improve file deletion performance for directories that contain a large number of files. Note that some applications depend on NTFS tunnel caching.
PagedPoolSize (no longer required for Windows Server 2008)
HKLM\System\CurrentControlSet\Control\SessionManager
\MemoryManagement\(REG_DWORD)
Disablelastaccess (no longer required for Windows Server 2008)
HKLM\System\CurrentControlSet\Control\FileSystem\(REG_DWORD)
NumTcbTablePartitions (no longer required for Windows Server 2008)
HKLM\system\CurrentControlSet\Services\Tcpip\Parameters\(REG_DWORD)
NoAliasingOnFileSystem (not applicable with SMB 2 clients)
HKLM\System\CurrentControlSet\Services\LanmanServer
\Parameters\(REG_DWORD)
TcpAckFrequency (no longer required for Windows Server 2008)
HKLM\system\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
General Tuning Parameters for Client Computers
HKLM\system\CurrentControlSet\Services\lanmanworkstation
\parameters\(REG_DWORD)
Windows XP client computers only. By default, this registry key is not created.
This parameter specifies the maximum number of files that should be left open on a share after the application has closed the file.
HKLM\system\CurrentControlSet\Services\lanmanworkstation
\parameters\(REG_DWORD)
Windows XP client computers only.
This is the number of seconds that the redirector waits before it starts scavenging dormant file handles (cached file handles that are currently not used by any application).
DisableByteRangeLockingOnReadOnlyFiles
HKLM\System\CurrentControlSet\Services\lanmanworkstation\parameters
\(REG_DWORD)
Windows XP client computers only.
Some distributed applications that lock parts of a read-only file as synchronization across clients require that file-handle caching and collapsing behavior be off for all read-only files. This parameter can be set if such applications will not be run on the system and collapsing behavior can be enabled on the client computer.
DisableBandwidthThrottling
HKLM\system\CurrentControlSet\Services\lanmanworkstation\parameters
\(REG_DWORD)
The default is 0. This setting is available starting with Windows Server 2008 SP2. By default, the SMB redirector throttles throughput across high-latency network connections in some cases to avoid network-related timeouts. Setting this registry value to 1 disables this throttling, enabling higher file transfer throughput over high-latency network connections.
HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\(REG_DWORD)
The default is 1 for client SKUs. By default, Windows automatically disables TCP receive window autotuning when heuristics suspect a network switch component may not support the required TCP option (scaling). Setting this value to 0 disables this heuristic and allows autotuning to stay enabled. When no faulty networking devices are involved, applying the setting can enable more reliable high-throughput networking via TCP receive window autotuning. For more information about disabling this setting, see “Resources.”
Performance Tuning for Active Directory Servers
The performance of Active Directory®, especially in large environments, can be improved by following these tuning steps:
Increase address space by using 64-bit processors.
For running Active Directory, 64-bit processors are preferred. Their large address space makes it possible to equip the server with enough RAM to cache all or most of the Active Directory database in memory. It also provides room for expansion to add RAM if the database size grows. For more information, see “Active Directory Performance for 64-bit Versions of Windows Server 2003” "Resources."
Increase user-mode address space on 32-bit x86 servers.
On servers that have 32-bit x86 processors, use the IncreaseUserVA boot option to increase user-mode address space. This increases how much virtual address space is available to Active Directory and lets Active Directory improve its caching. This option can be set by using the bcdedit tool as follows:
bcdedit /set IncreaseUserVA 3072
This option is the equivalent of the /3GB boot.ini option in Windows Server 2003.
Use an appropriate amount of RAM.
Active Directory uses the server’s RAM to cache as much of the directory database as possible. This reduces disk access and improves performance. Unlike Windows 2000, the Active Directory cache in Windows Server 2003 and Windows Server 2008 is permitted to grow. However, it is still limited by the virtual address space and how much physical RAM is on the server.
To determine whether more RAM is needed for the server, monitor the percentage of Active Directory operations that are being satisfied from the cache by using the Reliability and Performance Monitor. Examine the lsass.exe instance (for Active Directory Domain Services) or Directory instance (for Active Directory Lightweight Directory Services) of the Database\Database Cache % Hit performance counter. A low value indicates that many operations are not being satisfied from the cache. Adding more RAM might improve the cache hit rate and the performance of Active Directory. You should examine the counter after Active Directory has been running for some time under a typical workload. The cache starts out empty when the Active Directory service is restarted or the machine is rebooted, so the initial hit rate is low.
The use of the Database Cache % Hit counter is the preferred way to assess how much RAM a server needs. Or, a guideline is that when the RAM on a server is twice the physical size of the Active Directory database on disk, it likely gives sufficient room for caching the entire database in memory. However, in many scenarios this is an overestimation because the actual part of the database frequently used is only a fraction of the entire database.
Use a good disk I/O subsystem.
Ideally, the server is equipped with sufficient RAM to be able to cache the “hot” parts of the database entirely in memory. However, the on-disk database must still be accessed to initially populate the memory cache, when it accesses uncached parts of the database and when it writes updates to the directory. Therefore, appropriate selection of storage is also important to Active Directory performance.
We recommend that the Active Directory database folder be located on a physical volume that is separate from the Active Directory log file folder. In the Active Directory Lightweight Directory Services installation wizard, these are known as data files and data recovery files. Both folders should be on a physical volume that is separate from the operating system volume. The use of drives that support command queuing, especially SCSI or Serial Attached SCSI, might also improve performance.
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